Water-based inorganic anti-cracking, anti-seepage and waterproofing agent and preparation method thereof

Abstract

This invention belongs to the technical field of concrete admixtures, specifically relating to a water-based inorganic crack-resistant, seepage-proof, and waterproof agent and its preparation method. The crack-resistant, seepage-proof, and waterproof agent is composed of the following raw materials in parts by weight: 2-5 parts polyferric sulfate, 17-23 parts crystallizing agent, 0.8-1.5 parts synergist, 5-10 parts micro-expansion repair agent, 0.5-1 part filler, and 60-70 parts water. The micro-expansion repair agent is prepared by the following process: boron nitride fibers are plasma-treated and then added to water, followed by the addition of aluminum nitrate. The pH is adjusted to 8-10, and the mixture is stirred and reacted at room temperature. After filtration, washing, drying, and calcination, the micro-expansion repair agent is obtained. Using this crack-resistant, seepage-proof, and waterproof agent as a concrete additive can improve the crack resistance, waterproofing, seepage resistance, and mechanical strength of concrete.

Description

Technical Field

[0001] This invention belongs to the field of concrete admixture technology, specifically relating to a water-based inorganic crack-resistant, seepage-proof, and waterproof agent and its preparation method. Background Technology

[0002] Cement-based materials are the most widely used building materials in modern construction engineering, and their long-term durability and mechanical properties are crucial. Excellent waterproofing and seepage resistance are key to ensuring that concrete structures can resist environmental erosion and maintain functional integrity within their design service life. Traditionally, adding waterproofing agents to concrete to improve its seepage resistance has been the mainstream technical approach. These additives mainly function based on two principles: densification and hydrophobicity. Densification waterproofing agents (such as certain inorganic salts and silica powders) aim to react with cement hydration products to generate a gel that fills capillary pores and refines the pore structure. Hydrophobic waterproofing agents (such as fatty acid salts and organosilicon derivatives) form a hydrophobic film on the pore walls, reducing water adsorption and capillary action, thereby blocking the migration of liquid water.

[0003] However, engineering practice shows that waterproofing agents relying on the aforementioned traditional mechanisms have significant limitations. Firstly, traditional dense-type waterproofing agents primarily work by blocking capillaries and microcracks. They are ineffective at sealing existing larger cracks or new cracks caused by loads and deformations in the later stages of construction, resulting in insufficient overall crack resistance. Furthermore, concrete, as a non-homogeneous multiphase composite material, is inevitably affected by drying shrinkage, temperature changes, and loads during hardening and use, leading to the generation and development of micro and even macroscopic cracks. These dynamic cracks provide rapid entry channels for moisture and corrosive ions (such as chloride and sulfate ions), significantly reducing the effectiveness of waterproofing measures targeting only the original capillary pores. While traditional hydrophobic waterproofing agents can block moisture, they also affect the early moisture exchange in concrete: internal moisture is difficult to evaporate, and external curing water is difficult to penetrate and replenish. The surface may even be more prone to plastic shrinkage cracking due to impeded moisture migration. Simultaneously, once macroscopic cracks develop in the concrete, the hydrophobic membrane also breaks down, significantly reducing its waterproofing performance.

[0004] Therefore, the industry urgently needs a new type of solution that can provide effective mechanical properties and initial waterproofing capabilities in the early stages of concrete without interfering with the normal hydration process; at the same time, it should be able to adapt to the volume deformation of concrete, inhibit or repair the generation and development of microcracks, reduce the risk of cracking caused by early environmental changes, and thus truly improve the long-term durability of the structure. Summary of the Invention

[0005] The primary objective of this invention is to provide a water-based inorganic crack-resistant and waterproofing agent that, when added to concrete, can improve the concrete's impermeability, waterproofing, crack resistance, and mechanical properties.

[0006] The second objective of this invention is to provide a method for preparing the above-mentioned water-based inorganic crack-resistant and waterproof agent.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A water-based inorganic crack-resistant, seepage-proof, and waterproofing agent, wherein the crack-resistant, seepage-proof, and waterproofing agent is composed of the following raw materials in parts by weight: 2-5 parts of polyferric sulfate, 17-23 parts of crystallizing agent, 0.8-1.5 parts of synergist, 5-10 parts of micro-expansion repair agent, 0.5-1 part of filler, and 60-70 parts of water; The micro-expansion repair agent is prepared by the following process: Boron nitride fibers were plasma-treated and then added to water. Aluminum nitrate was added to adjust the pH to 8-10. The mixture was stirred and reacted at room temperature. After filtration, washing, drying, and calcination, a micro-expansion repair agent was obtained.

[0008] The preparation process of the micro-expansion repair agent of the present invention is as follows: First, boron nitride fibers are plasma activated to increase the active sites on the fiber surface and improve the surface roughness, thereby improving the uniformity of subsequent loading; then, aluminum ions react with hydroxide ions under alkaline conditions to generate a basic aluminum hydroxide precursor. Through the coordination complexation of hydroxyl groups on the surface of activated boron nitride fibers with aluminum ions, the precursor is uniformly anchored on the rough sites on the fiber surface in the form of nanocrystals; finally, after calcination, the aluminum hydroxide precursor undergoes a dehydration and decomposition reaction, and finally a micro-expansion repair agent with alumina uniformly loaded on the surface of boron nitride fibers is obtained.

[0009] Furthermore, the plasma treatment is performed in an oxygen atmosphere, with a power of 100-200 W and a duration of 20-30 min.

[0010] Furthermore, the mass ratio of the boron nitride fiber to aluminum nitrate is 1:(0.4-0.6).

[0011] Furthermore, the stirring reaction time is 2-4 hours.

[0012] Furthermore, the calcination temperature is 330-350 ℃, and the time is 1-2 h.

[0013] Furthermore, the synergist is magnesium glycerophosphate.

[0014] Furthermore, the crystallizing agent is sodium silicate or potassium silicate.

[0015] Furthermore, the filler is calcium stearate.

[0016] The preparation method of the above-mentioned water-based inorganic crack-resistant and seepage-proof waterproofing agent includes the following steps: Polyferric sulfate, synergist, micro-expansion repair agent and filler are added to water and stirred for 10-15 minutes. Then crystallizer is added and stirred evenly to obtain the water-based inorganic crack-resistant and seepage-proof waterproof agent.

[0017] The beneficial technical effects of this invention are as follows:

[0018] 1. The crack-resistant, seepage-proof, and waterproofing agent provided by this invention includes raw materials such as polyferric sulfate, crystallizer, micro-expansion repair agent, and synergist. The components work together to make this crack-resistant, seepage-proof, and waterproofing agent a concrete additive, which can improve the crack resistance, waterproofing, seepage resistance, and mechanical strength of concrete.

[0019] 2. This invention incorporates a micro-expansion repair agent into the crack-resistant, seepage-proof, and waterproofing agent. This micro-expansion repair agent utilizes a plasma activation combined with a chemical loading process to uniformly anchor alumina nanocrystals onto the surface of boron nitride fibers. This structure enables the boron nitride fibers to form a three-dimensional network skeleton in concrete, effectively inhibiting the propagation of microcracks. Simultaneously, the uniformly loaded alumina on the fiber surface generates layered products such as calcium aluminate hydrate in the cement hydration environment, producing mild and continuous micro-expansion. This compensates for concrete shrinkage stress, reduces internal crack formation, and enhances the interfacial bonding between the fibers and the cement matrix, thereby simultaneously improving the crack resistance, mechanical strength, and impermeability durability of the concrete.

[0020] 3. This invention adds magnesium glycerophosphate as a synergist to the crack-resistant, seepage-proof, and waterproofing agent. The introduction of magnesium glycerophosphate further optimizes the microstructure and hydration process of concrete. The hydroxyl groups and phosphate groups in its molecule can synergistically adsorb onto the surface of cement particles, forming a dense adsorption film, which has a mild retarding effect, beneficial to the workability and early strength development of concrete. Furthermore, the magnesium hydroxide microcrystals generated by magnesium ions can also serve as nucleation sites for hydration products, promoting uniform product distribution. Later, phosphate groups participate in the reaction to generate hydrated calcium phosphate, which can further fill the capillary pores of concrete, enhancing the density and durability of the concrete. Attached Figure Description

[0021] Figure 1 This is a scanning electron microscope image of the micro-expansion repair agent prepared in Example 1 of the present invention. Detailed Implementation

[0022] The following is a further detailed description of the present invention in conjunction with specific preferred embodiments, and it should not be construed that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art, various simple deductions or substitutions can be made without departing from the concept of the present invention, and all such modifications and substitutions should be considered within the scope of protection of the present invention. Specific conditions not specified in the embodiments are performed according to conventional conditions or conditions recommended by the manufacturer. Unless otherwise specified, all reagents or instruments used are conventional products obtained through commercial channels.

[0023] The boron nitride fibers of this invention have a diameter of 5-10 μm; the basicity of the polyferric sulfate is 10-15%.

[0024] (I) Implementation Examples

[0025] Example 1

[0026] Example 1 provides a water-based inorganic crack-resistant and waterproof agent, which is composed of the following raw materials in parts by weight: 3 parts polyferric sulfate, 20 parts sodium silicate, 1 part magnesium glycerol phosphate, 8 parts micro-expansion repair agent, 0.8 parts calcium stearate, and 65 parts water. The micro-expansion repair agent is prepared by the following process: Boron nitride fibers were plasma-treated at 180 W for 25 min under an oxygen atmosphere. Then, the treated boron nitride fibers, aluminum nitrate, and water were added to water at a mass ratio of 1:0.5:11. The pH was adjusted to 9 using 1 mol / L sodium hydroxide, and the reaction was stirred at room temperature for 3 h. After filtration, washing, and drying, the mixture was calcined at 350 °C for 1 h to obtain the micro-expansion repair agent. A scanning electron microscope image of the micro-expansion repair agent is provided in this embodiment. Figure 1 As shown.

[0027] This embodiment also provides a method for preparing the above-mentioned water-based inorganic crack-resistant and seepage-proof waterproofing agent, the specific steps of which are as follows: Weigh out the polyferric sulfate, sodium silicate, magnesium glycerol phosphate, micro-expansion repair agent, calcium stearate and water according to the above weight proportions. Add the polyferric sulfate, magnesium glycerol phosphate, micro-expansion repair agent and calcium stearate to the water and stir for 12 minutes. Then add sodium silicate and stir evenly to obtain a water-based inorganic crack-resistant and waterproof agent.

[0028] Example 2

[0029] Example 2 provides a water-based inorganic crack-resistant, seepage-proof, and waterproof agent, which is composed of the following raw materials in parts by weight: 2 parts polyferric sulfate, 17 parts potassium silicate, 0.8 parts magnesium glycerol phosphate, 5 parts micro-expansion repair agent, 0.5 parts calcium stearate, and 60 parts water. The micro-expansion repair agent is prepared by the following process: In an oxygen atmosphere, boron nitride fibers were plasma-treated at 100 W for 20 min. Then, the treated boron nitride fibers and aluminum nitrate were added to water at a mass ratio of 1:0.4:10. The pH was adjusted to 8 using 1 mol / L sodium hydroxide. The mixture was stirred at room temperature for 2 h. After filtration, washing, and drying, the mixture was calcined at 330 ℃ for 1 h to obtain the micro-expansion repair agent.

[0030] This embodiment also provides a method for preparing the above-mentioned water-based inorganic crack-resistant and seepage-proof waterproofing agent, the specific steps of which are as follows: Weigh out the polyferric sulfate, sodium silicate, magnesium glycerol phosphate, micro-expansion repair agent, calcium stearate and water according to the above weight proportions. Add the polyferric sulfate, magnesium glycerol phosphate, micro-expansion repair agent and calcium stearate to the water and stir for 10 minutes. Then add sodium silicate and stir evenly to obtain a water-based inorganic crack-resistant and waterproof agent.

[0031] Example 3

[0032] Example 3 provides a water-based inorganic crack-resistant and waterproof agent, which is composed of the following raw materials in parts by weight: 5 parts polyferric sulfate, 23 parts sodium silicate, 1.5 parts magnesium glycerol phosphate, 10 parts micro-expansion repair agent, 1 part calcium stearate, and 70 parts water. The micro-expansion repair agent is prepared by the following process: In an oxygen atmosphere, boron nitride fibers were plasma-treated at 200 W for 30 min. Then, the treated boron nitride fibers, aluminum nitrate and water were added to water at a mass ratio of 1:0.6:12. The pH was adjusted to 10 with 1 mol / L sodium hydroxide. The reaction was stirred at room temperature for 4 h. After filtration, washing and drying, the mixture was calcined at 350 ℃ for 2 h to obtain the micro-expansion repair agent.

[0033] This embodiment also provides a method for preparing the above-mentioned water-based inorganic crack-resistant and seepage-proof waterproofing agent, the specific steps of which are as follows: Weigh out the polyferric sulfate, sodium silicate, magnesium glycerol phosphate, micro-expansion repair agent, calcium stearate and water according to the above weight proportions. Add the polyferric sulfate, magnesium glycerol phosphate, micro-expansion repair agent and calcium stearate to the water and stir for 15 minutes. Then add sodium silicate and stir evenly to obtain a water-based inorganic crack-resistant and waterproof agent.

[0034] (ii) Comparative Example

[0035] Comparative Example 1

[0036] Comparative Example 1 is basically the same as Example 1, except that the micro-expansion repair agent in Example 1 is replaced with a mixture of boron nitride fiber and alumina, wherein the mass ratio of boron nitride fiber to alumina is 1:0.5.

[0037] Comparative Example 2

[0038] Comparative Example 2 is basically the same as Example 1, except that magnesium glycerophosphate in Example 1 is omitted.

[0039] Comparative Example 3

[0040] Comparative Example 3 is basically the same as Example 1, except that the magnesium glycerol phosphate in Example 1 is replaced with magnesium phosphate.

[0041] (III) Test Examples

[0042] The waterproofing agents obtained in Examples 1-3 and Comparative Examples 1-3 were respectively incorporated into concrete at a dosage of 0.25 wt% of the concrete, and the performance of the concrete was tested.

[0043] According to JC / T474-2008 "Mortar and Concrete Waterproofing Agent", the compressive strength ratio (%), water absorption ratio (%), penetration height ratio (%), and shrinkage ratio (%) of concrete with added Examples 1-3 or Comparative Examples 1-3 were tested.

[0044] According to GB 8076-2008 "Specification for Concrete Admixtures", the bleeding rate ratio (%) and the difference in retarding time of concrete with added Examples 1-3 or Comparative Examples 1-3 were tested.

[0045] According to GB / T 50082-2024 "Test Methods for Long-Term Performance and Durability of Ordinary Concrete", early crack resistance tests were conducted on concrete with added Examples 1-3 or Comparative Examples 1-3. The results are shown in Table 1.

[0046] Table 1. Test results of waterproofing agent on concrete compressive strength, cracking, and water seepage.

[0047] As shown in Table 1, the waterproofing agents prepared in Examples 1-3 of this invention can improve the waterproofing, impermeability, and mechanical properties of concrete when added to concrete.

[0048] Compared to Example 1, Comparative Example 1, where the micro-expansion repair agent was replaced with a mixture of boron nitride fibers and alumina, showed a significant decrease in the compressive strength, impermeability, waterproofing, and crack resistance of the concrete. This indicates that the uniform loading structure of alumina on the surface of boron nitride fibers in the micro-expansion repair agent plays a crucial role in its performance. The specific reasons are as follows: First, after plasma treatment and calcination, alumina is uniformly anchored on the fiber surface in the form of nanocrystals, avoiding agglomeration and reacting more effectively with cement hydration products to generate layered crystals such as calcium aluminate hydrate, achieving gentle micro-expansion and filling interfacial gaps. Second, the loading structure makes the alumina and fiber bond more tightly, forming a continuous reinforcement system of fiber-alumina-cement matrix in the concrete. In contrast, alumina in a physical mixture is easily dispersed unevenly and cannot form an effective micro-expansion and hydration reinforcement zone around the fiber. In addition, the uniformly loaded alumina forms a micro-expansion zone around the fiber, which can compensate for shrinkage stress and reduce stress concentration. In contrast, alumina in a physical mixture cannot act directionally on the fiber-matrix interface, resulting in a decrease in crack inhibition ability.

[0049] Comparative Example 2 omitted glycerol magnesium phosphate, while Comparative Example 3 replaced it with magnesium phosphate. Comparative Example 3 showed lower performance than Example 1 in terms of setting time, compressive strength, and penetration height, indicating that glycerol magnesium phosphate, as an synergist, has a dual effect of synergistic retarding and structural enhancement. This is because the hydroxyl groups and phosphate groups in glycerol magnesium phosphate can synergistically adsorb onto the surface of cement particles, forming a dense adsorption film, slowing down the hydration rate, and achieving mild retarding. Simultaneously, magnesium ions can generate trace amounts of magnesium hydroxide microcrystals, aiding in the uniform distribution of early hydration products. Phosphate groups later participate in the formation of hydrated calcium phosphate, further filling pores and improving structural density. Magnesium phosphate, lacking the adsorption and regulation effect of glycerol groups, has a weaker retarding and microstructure optimization effect.

[0050] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them. The basic principles and main features of the present invention have been described above with specific implementation schemes. Based on the present invention, some modifications or substitutions can be made, but these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of protection claimed by the present invention.

Claims

1. A water-based inorganic crack-resistant, seepage-proof, and waterproof agent, characterized in that, The crack-resistant, seepage-proof, and waterproofing agent is composed of the following raw materials in parts by weight: 2-5 parts polyferric sulfate, 17-23 parts crystallizing agent, 0.8-1.5 parts synergist, 5-10 parts micro-expansion repair agent, 0.5-1 part filler, and 60-70 parts water. The micro-expansion repair agent is prepared by the following process: Boron nitride fibers were plasma-treated and then added to water. Aluminum nitrate was added to adjust the pH to 8-10. The mixture was stirred and reacted at room temperature. After filtration, washing, drying, and calcination, a micro-expansion repair agent was obtained.

2. The water-based inorganic crack-resistant and waterproofing agent according to claim 1, characterized in that, The plasma treatment is performed in an oxygen atmosphere, with a power of 100-200 W and a duration of 20-30 min.

3. The water-based inorganic crack-resistant and waterproofing agent according to claim 1, characterized in that, The mass ratio of boron nitride fiber to aluminum nitrate is 1:(0.4-0.6).

4. The water-based inorganic crack-resistant and waterproofing agent according to claim 1, characterized in that, The stirring reaction takes 2-4 hours.

5. The water-based inorganic crack-resistant and seepage-proof waterproofing agent according to claim 1, characterized in that, The calcination temperature is 330-350 ℃, and the time is 1-2 h.

6. The water-based inorganic crack-resistant and seepage-proof waterproofing agent according to claim 1, characterized in that, The synergist is magnesium glycerophosphate.

7. The water-based inorganic crack-resistant and waterproofing agent according to claim 1, characterized in that, The crystallizing agent is sodium silicate or potassium silicate.

8. The water-based inorganic crack-resistant and waterproofing agent according to claim 1, characterized in that, The filler is calcium stearate.

9. A method for preparing the water-based inorganic crack-resistant and waterproofing agent according to any one of claims 1-8, characterized in that, Includes the following steps: Polyferric sulfate, synergist, micro-expansion repair agent and filler are added to water and stirred for 10-15 minutes. Then crystallizer is added and stirred evenly to obtain the water-based inorganic crack-resistant and seepage-proof waterproof agent.

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